1. Field of the Invention
Embodiments of the present invention generally relate to DC-to-DC converters and, more particularly, to fly-forward converters capable of resetting the transformer core.
2. Description of the Related Art
DC-to-DC converters are devices used to convert a DC voltage at one level to a DC voltage at another level and may be used as power supplies to deliver power to a load. Such converters typically comprise a transformer, having primary and secondary windings wound around a common magnetic core. By opening and closing the primary circuit for appropriate intervals, control over the energy transfer between primary and secondary is accomplished.
Common DC-to-DC converter topologies include the forward converter and the flyback converter. In forward converters, a switch may be connected between the voltage source and the primary winding of the transformer to provide forward power transfer to the secondary winding of the transformer when the switch is on and conducting. In flyback converters, energy is accumulated in the transformer by closing the switch of the primary circuit and is subsequently released from the secondary winding by opening the switch.
To discharge the leakage inductance (i.e., the magnetizing energy) of the transformer in forward converters, the transformer core may be reset during the off period of the switch. Resetting is typically accomplished by employing additional circuitry, such as a third transformer winding in parallel with the primary transformer winding, or an inductor-capacitor (LC) resonant circuit electrically coupled to the secondary winding.